The purpose of the study is to identify early predictors of stable conduct problems in young children. Although previous research indicates that antisocial personalities have histories of childhood behavior problems, there is no scientific evidence by which to target young children at risk for developing antisocial patterns. This study assesses several known dispositional and familial correlates of antisocial personalities, with a particular focus on the development of self-regulation of angry and aggressive impulses. The findings will yield information for (1) profiling children at-risk for chronic problems, and (2) identifying factors which deter continuity of such problems. Patterns of continuity and discontinuity are to be examined in problem and nonproblem children beginning at age 4 through age 6. Observational data of children's emotional and behavioral control in a variety of interactions, psychophysiological recordings during different mood states, assays of biochemicals involved in behavioral regulation (such as serotonin), and cognitive assessment take place between ages 4-6. Psychiatric diagnoses and school adjustment are assessed between ages 6-7.